Yup. Been doing so for a long time, 720 before 740. Works fine.
Make sure wires are connected only Tx from iFly to Rx on Dynon and not bi-directional. I literally had to snip pin off of the usb to serial adapter plugged into the ifly. It seemed the Dynon was 'sending' something which I think confused the ifly as to what was actually connected and it quit sending NMEA out. One the ifly wasn't receiving anything it seemed to default to sending NMEA out over the serial port and the HSI/Autopilot on the Dynon started working. I've had it this way since 720 so not 100% sure the same problem exists on the 740 but my one way cable definitely still works.
i can track down baud rate settings and custom NNEA sentence settings for you next time I'm at the hangar.